updates

lib/fm_modulator.h

@@ -0,0 +1,11 @@
+#include "oscillator.h"
+
+typedef struct
+{
+    float frequency;
+    float deviation;
+    Oscillator osc;
+} FMModulator;
+
+void init_fm_modulator(FMModulator *fm, float frequency, float deviation, float sample_rate);
+float modulate_fm(FMModulator *fm, float sample);